University Park, Pa. -- As the public and various interest groups debate the relative pros and cons of different egg-production practices and poultry-housing options, poultry scientists in Penn State's College of Agricultural Sciences say modern, science-based methods are helping to meet consumer demand for safe and nutritious eggs.

Whether production practices use conventional cages or cage-free methods, researchers and producers have found advantages and disadvantages in each system for the birds, for farmers and for consumers.

"As it stands now, consumers have choices, such as whether eggs are produced in conventional housing or cage-free, whether eggs have white or brown shells, whether eggs have higher levels of nutrients such as omega-3 fatty acids, or whether they were produced under certified-organic guidelines," said Gregory Martin, a Penn State Cooperative Extension poultry educator based in Lancaster County.

"Once you take any of those alternatives away, you reduce choice and competition and create artificial barriers in the marketplace," he said. "Ultimately, that could hurt consumers in the form of higher food prices and fewer options for obtaining high-quality dietary protein."

Martin noted that as much as 85 percent of Pennsylvania's eggs are produced under quality-assurance guidelines established by the United Egg Producers. Eggs labeled with the UEP seal are certified to have been produced in accordance with the industry group's best practices for animal husbandry, which were developed by an independent panel of scientists primarily from land-grant universities.

Reviewing the scientific literature on such factors as housing, space, feed and water, the panel considered all types of egg-production systems and concluded that all have their advantages and disadvantages, and that both cage and noncage production systems are humane and ethical.

In comparing different systems, Martin lists several advantages associated with conventional cage production:

-- As waste falls through the bottom of the cage and is collected below, birds are better separated from manure, keeping hens and the eggs they lay cleaner and less likely to contact manure-borne pathogens.

-- Birds can be individually inspected for signs of disease or other health issues in cage systems.

-- Feed efficiency is maximized compared to cage-free systems because there is less competition for feed and water.

-- In general, cannibalism and mortality may be lower in cage production.

Martin said the primary advantage of cage-free housing is that birds can roam free and engage in their full range of natural behaviors, such as nesting, perching and dust-bathing.

Cage housing began in the 1950s as a way to improve efficiency and better care for flocks, according to Paul Patterson, professor of poultry science. He said producers soon found benefits to this system, including better hen health, less exposure to disease-causing microorganisms, and protection from predators and extremes in environmental conditions associated with being outdoors.

"U.S. Department of Agriculture data for quality show fewer cracked and dirty eggs when hens are in cages," Patterson said. "Also, egg interior quality, including albumen height and freshness, are superior in eggs produced by hens in cages.

"In addition, we now know these modern cage systems actually benefit the environment by generating less ammonia and odors, because farmers are better able to manage the manure and maintain water quality," Patterson noted.

Patterson said one study estimated that because cage-free production is less efficient -- with birds eating 15 to 25 percent more feed and producing fewer eggs -- 3 billion additional pounds of corn and soybean meal would be needed if all egg production were converted to cage-free. "The study estimated that 580,000 more acres of cropland, as well as additional fertilizer and fuel, would be needed to grow these feedstuffs," he said.

The reduced efficiency and labor-intensive nature of cage-free systems is the primary reason that cage-free eggs are more expensive in the retail marketplace. A recent USDA weekly price report, based on a survey of thousands of retail outlets, showed large Grade A white eggs selling for an average of $1.20 per dozen, compared to $2.74 per dozen for white cage-free eggs. The study cited by Patterson estimates that switching to all-cage-free production would increase consumer egg costs by about $2.6 billion annually.

Martin said some consumers are clearly willing to pay that premium, as cage-free eggs account for about 5 percent of market share. But the cost may be prohibitive for large food-service operations serving thousands of customers. "Based on per capita average annual consumption, switching to cage-free eggs would cost nearly $35 more per person each year," he said. "Multiply that by tens of thousands of people -- such as are served at a large university like Penn State -- and you'd be talking about adding hundreds of thousands of dollars or more to the food-purchasing budget.

"And because there aren't nearly as many cage-free producers, you might encounter spot shortages in the market that could disrupt operations," he added.

Patterson agrees with Martin that it's important to generate and disseminate the scientific knowledge needed to improve hen well-being and efficiency in all production systems if the egg industry is to maintain and enhance consumer choice. But he said, based on his experience, cage systems have the most advantages.

"After 30 years raising and researching hens in all housing and pasture systems, I believe that hens are better off in cages," he said. "Here, farmers can better see and manage their birds daily, listen to their cooing and clucks, and watch out for their health and welfare -- and the quality of their eggs for American consumers."